Abstract:
Several approaches are evident in the literature to improve the fatigue
resistance and lower the leakage current densities of PZT thin films for nonvolatile
random access memory (NVRAM) application. We have
undertaken an approach of doping (conventional and graded) of PZT
(53/47) thin films with Fe cation, which tend to occupy B-site in the AB03
unit cell. Our studies indicated several improvements in the electrical
characteristics. The graded doped Fe film of similar dopant concentrations
exhibited even better fatigue behavior up to -lo9 cycles. In addition, the
Ohmic behavior in I-V characterization extended up to 250 kV/cm for
graded doped films, while the non-linearity sets at much lower field
(lSOkV/cm) for undoped films at room temperature. Conventional doping
improved the electrical behavior as compared to undoped films. However,
the graded doped films exhibited even further improved electrical behavior
in terms of reducing leakage current by at least an order of magnitude under
an applied electric fields of about 150 kV/cm.